Mesoscale circulation determines broad spatio-temporal settlement patterns of lobster

Area of Science:

• Marine Ecology
• Physical Oceanography
• Fisheries Science

Background:

• Larval dispersal is vital for marine species' ecology and sustainable fisheries.
• Understanding oceanographic influences on larval supply is key to predicting settlement patterns.

Purpose of the Study:

• To investigate how ocean currents shape larval dispersal and settlement for the Eastern Rock Lobster (Sagmariasus verreauxi).
• To determine the extent to which ocean circulation patterns dictate settlement success along the continental shelf-break.

Main Methods:

• Correlating a 21-year dataset of observed Eastern Rock Lobster settlement with simulated larval settlement.
• Utilizing an eddy-resolving, data-assimilated hydrodynamic model incorporating species-specific spawning and larval duration.
• Analyzing the influence of the East Australian Current (EAC) and mesoscale eddies on larval transport.

Main Results:

• Mesoscale circulation patterns explain broad spatio-temporal settlement variability, including inter-annual and decadal changes.
• The latitude of the East Australian Current's deflection dictates settlement boundaries.
• Years with persistent EAC flow showed low settlement, while years with prevalent mesoscale eddies exhibited high settlement.

Conclusions:

• Mesoscale eddies are crucial for transporting Eastern Rock Lobster larvae to the continental shelf-break.
• Satellite-observed circulation features can serve as proxies for predicting broadscale settlement patterns.
• These predictions can aid in setting sustainable harvest limits for fisheries.